Blowpipe nozzle



May 22, 1945.

R. S. BABCOCK BLOWPIPE NOZZLE Filed Feb. 26, 1941 INVENTOR ROGER s.BABCOCK BY ATTORNEY Patented May 22, 1945 BwwmrnNozun Roger s. Babcock,Plainfield, N. 1., assignor Union Carbide and Carbon Corporation, acorporation of New York Application February 26, :1941, Serial No.380,848 1 This invention relatesto ablowpipe nozzle and moreparticularly to airy-acetylene cutting blows pipe nozzles for cuttingmetallic bodies in which a stream of oxidizing gas, such as oxygen, isapplied to a portionof the metallic body preheated by a flame producedby the combustion of a mixture of oxygen and acetylene.

Oxy-acetylene cutting is a process of severing ferrous metals byutilizing the rapid chemical reaction which takes place between heatediron and oxygen. The heat liberated by this reaction is suflicient notonly to melt the iron oxide but also to melt some of the steel or iron.(In a practical application of the oxy-acetylene cutting process, theJet or stream of oxygen which does the "cut ting issues from an orificein the center of a nozzle or tip of a cutting blowpipe. Surrounding thecutting orifice oi the nozzle or tip are several smaller orifices foroxy-acetylene heating flames. These are used to preheat the metal to itskindling temperature. Theoretically, the heat of the cutting reactionshould be sufficient to keep the cut going after it has started. Inpractice, however, the heating flames arekept burning constantly to meltthe surface scale and thereby insure the proper reaction with continuousand rapid cutting. The flow of cutting oxygen is controlled by aconveniently located valve on the blowpipe handle, and the cuttingoxygen jet may be guided along any line desired, whether straight,curved, or irregular, and may also be inclined at an angle, as indeseaming.

To start cutting, the blowplpe is held with the nozzle perpendicular tothe surface of the work and with the inner cone of the heating flameabout inch above the end of the line to be cut on the edge of the work.The blowpipe is held steady until this spot has been raised to'a brightred heat, and the cutting valve lever is then pressed down slowly whilemoving the blowpipe along the line to be cut. If the out has startedpromptly, a shower of sparks will fall from the underside of the work,thus indicating that the cut is penetrating clear through. The movementof the blowpipe is then regulated Just fast enough so that the cutcontinues to penetrate the work completely.

As used throughout this specification and in the claims, the termoxy-acetylene cutting is intended to include all o'xy-acetyleneworkingof ferrous metals, such as scarfing, deseaming, desurfacing, grooving,slotting, severing, and the like.

The principal obiect of this invention is to pro.

1 Claim. (Cl. 158-274) erating characteristics superior to those nowknown. Other objects of this invention are to improve both cutting anddeseaming nozzles in general by providing means associated therewith for5 increasing the overall efliciency of the thermochemical reaction; toproduce smoother and more uniform reaction zones by controlling theradial expansion of the cutting gas; to obtain a ring preheat flame,theuniformity of which, being essentially independent of the number oforifices producing said ring flame, increases the cutting e1- ficiency;to provide an oxy-acetylene nozzle having a skirt extending beyond thenormal face of the nozzle, the size of said skirt being proportioned toobtain the, best operating characteristics of the nozzle; to provide animproved means for utilizing discharged preheat gases to retard theradial expansion of the oxygen jet discharged by an oxygen orifice tothereby ingo crease the axial velocity of. the oxygen jet to a valueabove the acoustic.

According to the invention there is provided a blowpipe nozzleconsisting of a conventional cutting or deseaming nozzle having acylindrical 25 flange or skirt extending beyond the normal face thereof.The skirted portion is constructed in a manner whereby a sufiicientquantity of the heat induced therein will be conducted backto the.nozzle body, preventing deterioration 01' such skirt and increasing theheat content of the preheat gas, which increase in heat content of thegas improves the overall efiiciency of the nozzle. In addition to theconstruction and arrangement of the skirt to properly utilize theinduced heat, it also has internal dimensions, which, in conjunctionwith the arrangement and size of the preheat and cutting oxygenorifices, produce a ring preheat flame and an oxygen stream havingdivergent Jet characteristics.

More particularly, according to the invention, the skirt extends beyondthe normal face of the nozzle so that the skirt opening, coupled withthe exhausting preheat gases, retards the radial expansion of the oxygenjets beyond the oxygen orifice and thereby increases the axial velocityof the oxygen Jet to values above the acoustic. For best results, it hasbeen determined by actual tests, that the skirt should have a lengthequal to or greater than the lengthof. the inner cone of the preheatingflame. Further, that the internal diameter of the skirt adja'centto thenormal face of the nozzle should be equal to or greater than the sum ofthe diameter of the proheat hole circle plus the diameter of one preheathole. preferablv mural a. ma cum y. 4k. Munof said circle plus the widthof three of said precuttings-swell. The nozzle i3 is surfaces,

heat holes. in addition the preheat hole circle should have a diametersubstantially equal to one and one-half that of the cutting oxygenorifice. The skirt itself may be either cylindrical, convergent, ordivergent, the diameter of the skirt being measured at the rearmostportion thereof. Referring to the accompany! drawing:

' 'Fig. 1 is a view in side elevation of a cuttingblowpipe having anozzle embodying features of thisinvention: Fig. 2 is an enlargedfragmentary cross-sectional view of the head portion of the blowpipeshowninl lg. 1; v

Fig. 3 is an enlarged fragmentary sectional similartol 'igz'ofthenozzletip;

'l igJisaplanviewoftheendofthenozzie view 1 shown in m. 3:

Fig.5 is a fragmentary sectional viewshowing the nozzle in operation:and

' F 88; 6 and 1.81% longitudinal and Wet sections, showing the use ofthe nozzle in cutting a body steel, 7 being taken-on line |-,-I of Fig.6;

the cutting blowpipe ll, shown by way'of example, an oxy-acetylene flameii is produced at a series of preheat gas openings I! in the blowpipetip'or nozzle it, which surround a larger- "the blowpipe through a hosell while acetylene issupplied to the blowpipe through a hose Thuscutting oxygen is delivered to central passageway SI of the nozzl l3through pipe 32, while a combustible mixture of oxygen and acetylene isdelivered through pipe 33 to the preheating Gas 4 orifices I! whichsurround the cutting oxygen oriflce 84 in the normal end face 34 of thenozzle.

According to the invention, both one and twopiece nozzles are equallyefficient and the addition of a skirt to otherwise conventionaloxy-acetylene nozzles having either a conical divergent cutting oxygenorifice or a cylindrical cutting oxygen orifice, was found to have adefinite beneflcial effect upon the operation of the nozzle.

The skirted nozzle, shown in the drawing by way of example, consistsessentially of an outer body or casing 35 and an inner member 38 con-.taining the central oxygen passage ll terminating in orifice l4, and thepreheat gas ports it. The

snember 86 is shown connected to partfl by a nipple 38 but may beintegral with the latter. The

outer casing 35 has a cylindrical flange 39 on the rear portion thereofadapted to be engagedby the externally threaded nut 16 which surroundsthe casing 35 and secures the nozzle II to the blowpipe head 25. Thebody thickness of this outer member 35 must be great enough to conduct asufficient quantity of 'heat from skirt 48 to prevent damage to theskirt 40 by reason of its close proximity to the high temperature flameSuch hoses areconnected to the blowpin M by tions 2| and 22,respectively, the supply of oxygen, and acetylene being adjusted byvalves and 24.- Oxy en and acetylene are mixed within-the blowpipe toprovide a suitable combustible mix-v j ture for supplying the preheatingflame, while the cutting oxygen is conducted directly fromthe nozzle I:by .way of the cut l il oxygen, valve.

Conventional oxyeacetyiene cutting blowpipes are of either thelow-pressure, or medium-pres .sure type. -Simply by changing the size ofthe cutting-,nozzle or cutting tip, a single cutting biowpipe may beadapted to cut a wide range of;

- the preheat gas to flow through the reheat or- Y names used on cuttingblowpipes may be of either metal thickness. Furthermore, interchangeableone-piece or two-piece construction. In the onell emanating from thepreheat ports I2. The

inner member-3B, nipple 38 and part 31, generally cylindrical in shape,are slightly smaller than the inner diameter of easing It in order to.provide an annular passageway 42 for the oily-I A On the rear portionof acetylene gas mixture.

part 31 of the inner member 38 is a cylindrical flange 43, the forwardsurface of which coacts with the cylindrical flange 39 on the casing SIf. toformagas-tightseal. 1 I Y The inclined seats 21 and 28 coactingwith the corresponding seats 29 and 30 in theblowpipe '1 7 head .25,form gas-tight seals and prevent the mixture of the preheat gas with thecuttingoxygen as these gasses pass from the blowpipe head "45 2! tonozzle passages 3| and 44, respectively. On oxygen inlet ii to,the'central orifice 14 of the the forward portion of the inner member 38is a ;conical flange 45 in which the series of preheat gas ports [2 areannularly disposed and concen- .trically aligned with the central oxygenorifice 5 I4.- This conical flang 45 conforms in shape .lwithfitheforward conical portion of the casing 35,

face it and longitudinal axes C of the preheat orifices l2 form includedangles of about 9 and heating flames and cutting jets are drilledthrough I a solid piece of metal, usually pure copper.., The

cutting, cast-iron cuttinmsheet-metal cutting, I

* 'desin'facing, and d. While a'hand-cut-j ting blowpipe has been showninthe drawing, it

will be understood that the invention isnot lixnited thereto, butincludes or of the one-piece swaged type. Such types are biowpipes formachine secures a artments m of the blowpipe II by means of a hollow notI.

which is threaded into the head a and forces seating surfaces 21 and 28on the nozzle into seal-q Inthe example of the nozzle 00 "5,respectively, with the longitudinal axis of the.

cutting oxygen orifice l4. 7 i

illustrated in Fig. 2, the inner piece of the two-piece nozzle consistsof the member 38 and'part 31 connected by the nut 38 However, it will beunderstood by those skilled in: the art that the entire inner piece mayconsist of a single member of conventional style..-, The nozzle-may alsoconsist of the so- "called Zobel type, or the conical divergent type,

well known to those skilled in the art.

Referring to Fig. 3, from experiments actually conducted on skirtednozzles, according to the invention, it has been found that the diameterB of the preheat hole circle should be about one and one-half times thediameter of the cutting oxy en orifice l4. and that the internaldiameter F of the skirt 40, for good results, should be approximatelyas'rausequal to or slightly greater than the sum of the upon the normallength of the inner cone ll, Fig. 5, of the preheat flame II and shouldbe equal to or slightly longer than the inner cone I. It has also beenobserved that when cutting work with the skirted nozzle It, the tendencyfor slag t find its way into the preheat holes I! is almost completelyeliminated and therefore permits the use of a large number of smallpreheat flame ports I! when necessary.

In operation, the preheat flames emanating from the series of ports areadjusted so that the inner cone I does not extend beyond the innersurface of the skirted portion I. The oxygen stream 41 emanating fromthe central oriflce I4 partially fllls that area surrounded by the skirt40 and allows a narrow space for the passage of the outer envelope 48 orthe gases forming the preheat flame II. By so. confining the outerenvelopes of the individual flames, a ring flame isessentially obtained,adding to the efllciency of the nozzle and eliminating the necessity foran excessively large number or small preheat gas ports 12. Furthermore,it has been found that, with a properly designed skirt 40, the outer an-"nular envelope 48 of the preheat flames II, which surround the oxygenstream '41, extends approximately 10 to 12 inches beyond the face of thenozzle I 3. When employing the cylindrical bore cutting oxygen oriflceil in the skirted nomle J8, the usual radial expansion of the gas 41upon being discharged into the atmosphere is partially prevented becauseof the cushioning efiect provided by the presence of the annular heatingflame 48, producing let characteristics very similar to those obtainedfrom a conical divergent nozzle, as evidenced. by the kerf contour.

The stream shape shown in Fig. 5 is representative of that obtained witha skirted cylindrical nozzle l3 constructed in accordance with theinvention. The length, uniformity and sym-* metry of the outer preheatenvelope 48 is strikinsly obvious and the outer envelope It does notundergo any great degree of radial expansion which condition, of itself,indicates that a great part of the heat is efliciently applied to thecutting area to aid the operation.

Referring to Figs. 6 and 7, a steel body 48 is shown being cut by theoxygen stream 41 of Fig. 5 assisted by the oxy-acetylene heating flameIt. The nozzle II is constructed and arranged to cause the zone ofsecondary combustion of said flame to flow with the cutting oxygen toform a composite cutting stream in which the cutting oxygen issurrounded by a single well-defined heating flame. The skirtedcylindrical bore nozzle I3 is definitely superior, in cutting the steelbody 48, than any known non-skirted nozzle because the walls 50 of keri5| are smoother and the actual operating eiiicien-cy is higher.

Among the advantages of the skirted nozzle of the invention, over thoseformerly known, may bellsted: the high overall efliciency of theoperation because of the added heat applied to the work, smoother andmore uniform cuts because of the added heat and the production oi anessentially ringyp flame.

It has been round, through investigation, that the amount of heatapplied to a metal body during a conventional cutting operation has aniniurious effect upon the resultant keri walls, in that an oxidiccoating formed on these walls, in such instances, becomes loose andpieces thereof are drawn into and disrupt the cutting stream. 'ihc mostprobable cause of such loosening of oxide is the insufliciency of heat,that is, the oxide is formed through the combustion of the steel andwithin a short interval of time, with ordinary nozzles, sufllcientcooling may take place to cause theoxide to chip, because of thecontraction of the base metal.

into the keri 5|, Figs. 6 and 7, and keeps the oxide closer to thetemperature of the adjoining basemetal ,so that the outside cools moreslowly and there is no chipping or loosening of the scale in thevicinity of the reaction zone. This condition results in the productionor highly smooth and uniform walls Iii.

It is known that a skirted nozzle hasheretofore been used, primarily asa matter of necessity, especially with gases other than acetylene, suchas propane, having a relatively low rate oi flame propagation comparedto the oily-acetylene flame. With such iuel gases, the normal linealvelocity of gas at the mouth of the nozzle greatly exceeds the rate offlame propagation and causes the flame to be blown away-irom the face ofthe nozzle. To overcome this difliculty, a means must be employed todecrease the gas velocity at the periphery of the gas stream withoutaffecting the internal velocity of, the stream as merely in order toinsure stable operation of the apparatus. A skirted nozzle for fuelgases other than oxy-acetylene was, therefore, adapted for such purposeand has since been considered standard practice. The skirtedtype ofnozzle 40 heretotore used for fuel gas other than acetylene,

,gtarding the normal free expansion of the oxygen stream outside of the.oxygen oriflce. If the such as propane, was not intended to be used forcity-acetylene cutting because, due to the, intense heat of theoily-acetylene flame, the skirted portion of the nozzle was quicklyburned away. Therefore, the development of the art was such that nozzlesfor oxy-acetylene cutting inair generally had a smooth non-skirted endface,. while cutting nozzles for fuel gasps other than normal expansionis retarded by the presence of a surrounding medium moving at a velocitysomewhat less than the acoustic, but appreciably faster than thesurrounding air streams, then radial expansion of the oxygen stream willbe retarded and an increase in the axial expansion away from the oriflcemust result. Such a theory presupposes less turbulence in the oxygenstream and a more uniform keri width. These have generally been observedin actual tests with cuttnlg nozzles embodying the invention.

The skirt material should be able to withstand the heat from theoxy-acetylene flame or to have a conductivity high enough to preventlocalised heat from melting the lkiitid section. Th8! However, with askirted oxy-acetylene nozzle made and used according to the invention,additional heat is drawnconditions are satisiactorily ioundin the use oicopper which is cheap, readily machined,- and already used in nozzleconstruction. The skirt should be an extension of the nozzle, in theoneiece construction, oran extension oi the externai member if made oftwo-piece construction. Buiiicient material should be'allowed in thesection adjoining the skirt of the nozzle body to provide for therequired heat transfer.

Among the more important features of the present invention are thefollowing:

1. Theuse of a skirt section extending beyond the normal face of anoxy-acetylene nozzle.

This is only possible for high flame-temperature gases, through thespacing of the preheat holes between the oxygen orifice and thesurrounding skirt, so that the preheat flame cones do not contact theskirt. Absorption of heat by the skirt is therefore reduced because theflames do, not contact the skirt material. The heat picked up throughconvection and radiation is of a relatively small amount.

2. The use of a skirt section involving preheat and skirt dimensionswithin certain proportional limits for optimum operation withoily-acetylene.

By holding the dimensions within certain limits,

satisiactory operation or the nozzles can be re- 'strlcted to the use ofoxy-acetylene alone. The time intensity of other commercial fuel gasesis so low by comparison with the more rapidly burning on-acetyleneflames that their use with the optimum, skirted, oxy-acetylene designnozzle is precluded.

3. The use of a skirted section extending be- I yond the normal face ofthe nozzle so that the skirt opening, coupled with the exhaustingpreheat gases, retards the radial expansion of the oxygen jet beyond theoxygen orifice and thereby by increases the axial velocity of the oxygenJet to values above the acoustic.

Keri samples of cuts made with skirted, cylinout this point.

asraue drical bore;;oxy-acetylene nozzles seem to bear will out fasterand more eiliciently than known o'xy-iuel gas nozzles which are notsuited to the high temperature of the oxy-acetylene flame. In

such skirted oxy-acetylene cutting nozzles, the

diameter oi. the preheat hole circle should be held within a definiterelationshipto the diameter of the cutting oxygen orifice, and thediameter of the mouth or the skirt should be maintained within certainlimits with respect to the preheat hole circle.

What is claimed is:

A blowpipe nozzle having an end face, a central cutting oxygen orificeterminating at said end face and adapted to discharge a cutting streamof oxygen, a plurality of oxy-acetylene preheating gas ports terminatingat said end face in a circle concentric with said orifice. and adaptedto discharge Jets 0! oxy-acetylene preheating gas which, when ignited,produce flames each having an inner cone and an outer heating envelope,andmeans for merging and concentrating said outer envelope symmetricallyabout said cutting stream for a substantial distance axially thereofinto a single annular heating flame, said means comprising an annularskirt on said nozzle adaptedto surround said fiames in concentricrelation with said oxygen stream, said skirt having an inner diameteradjacent to said lace equal to the sum of the diameter of said circleand the width of three oi said ports, said circle havinga diameter equalto substantially one and one-halt times the diameter of said orifice. IROGER S. BABCOCK.

' Radial drilllngs through ,sklrted section emitted preheat names undernoimalconditions which indicatedfthat a slight 'back pressure existswithin the skirt 'cavity. 1 1 In conclusion, skirted oily-acetylenenozzles constructed according to the invention

